Electromagnetic flowmeter features
Frequency programmable low frequency rectangular wave excitation improves stability of flow measurement and low power loss.
The new 16-bit ultra-low power microprocessor with FLASH memory has high integration, fast calculation speed and high calculation accuracy.
Full digital processing, strong anti-interference ability and reliable measurement.
Ultra-low EMI switching power supply, suitable for power supply voltage variation range, high efficiency, small temperature rise; good EMC performance.
Chinese and English menu operation, easy to use, easy to operate, easy to learn and understand.
High definition backlight wide temperature LCD display.
It can perform bidirectional flow measurement and bidirectional total accumulation; it has automatic range switching function, which can effectively improve the measurement accuracy of analog current and frequency output, especially suitable for occasions where the diurnal flow range changes greatly and needs to send control signals; flow measurement range Up to 1500:1.
There are three totalizers inside, which record and display the forward cumulative amount, the reverse cumulative amount and the accumulated difference integrated amount, which are convenient for fluid metering and custody transfer.
Provide isolated or non-isolated RS485/RS232C digital communication interface, and support fieldbus communication modes such as MODBUS, PROFIBUS-DP and HART.
Constant current source fluid resistance measurement can accurately measure the internal resistance of the electrode signal in the case of long-line transmission. It can be used not only to determine whether the fluid in the sensor is empty or not, but also to identify abnormal phenomena such as contamination and coverage of the electrode, and to provide cleaning for the user. Fault processing information such as electrodes.
Ultrasonic flowmeter common problems (1)
1. The ultrasonic flowmeter probe is used for a period of time, and irregular alarms may occur. This problem is more common when there are more impurities in the transport medium. Solution: Clean the probe regularly (recommended once a year).
2. When the ultrasonic flowmeter transport medium contains liquid impurities such as water, the flow metering tube is prone to effusion, and the freezing of the pressure tube may occur when the temperature is low, especially in the northern regions in winter. Solution: Purge or electrify the pressure tube
3, the ultrasonic flowmeter is very strict on the requirements of the pipeline, there can be no abnormal noise, otherwise it will affect the measurement error.
During the propagation of ultrasonic waves, their strength is attenuated due to obstruction or absorption by impurities in the medium and medium. Whether it is an ultrasonic flowmeter or an ultrasonic level gauge, there is a certain requirement for the received sound wave intensity, so various attenuations are suppressed.
4. What is the instantaneous flow fluctuation?
The signal strength is large, and the measured fluid fluctuation is large.
Solution: Adjust the probe position, improve the signal strength, and ensure the signal strength is stable. If the fluid fluctuation is large, the position is not good. Re-select the point to ensure the 5D working condition after the first 10D.
How the turbine flow meter works
The working principle of the turbine flowmeter: the fluid flows through the sensor housing. Since the blade of the impeller has a certain angle with the flow direction, the momentum of the fluid causes the blade to have a rotational moment. After the friction torque and the fluid resistance are overcome, the blade rotates, and the rotational speed is stabilized after the torque balance. Under certain conditions, the rotational speed is proportional to the flow rate. Due to the magnetic permeability of the blade, it is in the magnetic field of the signal detector (composed of permanent magnet and coil). The rotating blade cuts the magnetic field lines and periodically changes the coil. Magnetic flux, so that the two ends of the coil induce electricity
Pulse signal, which is amplified and shaped by the amplifier to form a continuous rectangular pulse wave with a certain amplitude, which can be transmitted to the display instrument to display the instantaneous flow rate and cumulative amount of the fluid. Within a certain flow range, the pulse frequency f is proportional to the instantaneous flow rate Q of the fluid flowing through the sensor. The flow equation is: Q = 3600 × f / k
In the formula:
F——pulse frequency [Hz];
K——the meter factor of the sensor [1/m], given by the checklist. If [1/L] is used, Q=3.6×f/k
Q——the instantaneous flow rate of the fluid (under working condition) [m3/h];
3600 - conversion factor.
The meter factor of each sensor is filled in the verification certificate by the manufacturer, and the k value is set in the matching display meter to display the instantaneous flow rate and the cumulative total amount.